ATLANTA - The Coca-Cola Co. is betting big that Glaceau will help it expand its water and energy drink portfolio and jump-start sales in its North America unit as it announced a deal Friday to buy the privately held maker of Vitaminwater for $4.1 billion in cash.

Executives at the world's largest beverage maker said the price-tag, nearly twice Glaceau's estimated value less than a year ago, is worth it.

''We're looking at this as a long-term opportunity,'' Chief Operating Officer Muhtar Kent told reporters in a conference call.

John Sicher, an industry analyst and editor and publisher of Beverage Digest, said the price is a function of Glaceau's ''astronomical'' growth.

''There are simply no other privately owned brands out there which could give Coke the kind of potential Glaceau does,'' Sicher said. ''In addition, Coke can create more value by putting it into its strong international bottlers. That will further help make this deal pay off.''

The acquisition, Coca-Cola's largest ever, will be financed with debt, and is expected to add to Coca-Cola's earnings starting in 2008, but will slightly dilute profits this year, executives said.

Coca-Cola's chief financial officer, Gary Fayard, said in a conference call with analysts that Coke will take full ownership of Glaceau, which for now is 30 percent owned by holdings of India's Tata Group, a conglomerate with interests spanning steel, software services, hotels, chemicals and insurance. The Tata stake will be acquired later than the majority stake, Fayard said. Tata will get $1.2 billion of the $4.1 billion purchase price, officials said.

Tata paid $677 million for its Glaceau stake last August, a deal that at the time valued the entire company at $2.2 billion, Coca-Cola said.

The purchase of Glaceau, also known as Energy Brands Inc., could reduce Coca-Cola's financial flexibility to buy back its own shares. Coca-Cola had previously said it would buy $2.5 billion to $3 billion of its stock this year; Fayard said Friday the company now expects to repurchase at least $1.75 billion to $2 billion in shares in 2007.

Fayard said the company expects cost savings from the Glaceau deal to develop later, and he added that Coca-Cola will invest those savings in further growth of Glaceau's brands.

Formed in 1996 and based in Whitestone, N.Y., Glaceau is the maker of Vitaminwater, Fruitwater, Smartwater and Vitaminenergy.